import { Directive, forwardRef, Attribute } from "@angular/core";
import { Validator, AbstractControl, NG_VALIDATORS } from "@angular/forms";

@Directive({
  selector:
    // tslint:disable-next-line:directive-selector
    "[validateEqual][formControlName],[validateEqual][formControl],[validateEqual][ngModel]",
  providers: [
    {
      provide: NG_VALIDATORS,
      useExisting: forwardRef(() => EqualValidator),
      multi: true
    }
  ]
})
export class EqualValidator implements Validator {
  constructor(
    @Attribute("validateEqual") public validateEqual: string,
    @Attribute("reverse") public reverse: string
  ) {}

  private get isReverse() {
    // tslint:disable-next-line:curly
    if (!this.reverse) return false;
    return this.reverse === "true" ? true : false;
  }

  validate(c: AbstractControl): { [key: string]: any } {
    // self value
    // tslint:disable-next-line:prefer-const
    let v = c.value;

    // control vlaue
    // tslint:disable-next-line:prefer-const
    let e = c.root.get(this.validateEqual);

    // value not equal
    if (e && v !== e.value && !this.isReverse) {
      return {
        validateEqual: false
      };
    }

    // value equal and reverse
    if (e && v === e.value && this.isReverse) {
      delete e.errors["validateEqual"];
      // tslint:disable-next-line:curly
      if (!Object.keys(e.errors).length) e.setErrors(null);
    }

    // value not equal and reverse
    if (e && v !== e.value && this.isReverse) {
      e.setErrors({ validateEqual: false });
    }

    return null;
  }
}